The term 'toughens' can be defined as making something stronger or more resilient. The crossword solutions for this term are 'enures' (6 letters), 'inures' (6 letters), 'anneals' (7 letters), and 'STEELS' (6 letters). Enures is a verb meaning to become accustomed to something unpleasant, while inures is a verb meaning to become hardened to something unpleasant. Anneals is a verb meaning to heat and then cool metal in order to make it stronger, while STEELS is a verb meaning to make someone or something emotionally stronger. All of these words relate to the term 'toughens' in that they all refer to making something stronger or more resilient.